“Medulloblastoma occurs in 10%-20% of patients with basal cell nevus syndrome and can be the presenting sign. So if a patient with basal cell nevus syndrome gets medulloblastoma, it usually occurs within the first year of life – and it can be the first thing you see,” she said at the Hawaii Dermatology Seminar provided by the Global Academy for Medical Education/Skin Disease Education Foundation.

Dr. Huang presented a series of pediatric dermatology clinical pearls focused not only on basal cell nevus syndrome (BCNS) and medulloblastoma, but also on the implications of skin-limited Langerhans cell histiocytosis, how to recognize and treat drug-induced follicular eruptions in pediatric patients on targeted anticancer therapies, and when to suspect Demodex folliculitis in immunosuppressed patients.

Skin-limited Langerhans cell histiocytosis

Around 10%-20% of patients with Langerhans cell histiocytosis (LCH) have the skin-limited form of the malignancy. These are patients who, after a thorough workup, have a normal CBC, skeletal survey, and liver function tests; essentially, no evidence of multisystem disease.

Bruce Jancin/MDedge News

Dr. Jennifer Huang

A pair of studies published several years ago provide guidance on how to best manage such patients. In one study of 26 patients with LCH with skin involvement, 16 had skin-limited LCH which was present at birth and 10 had multisystem disease. During a mean 19.5 months of follow-up only 1 of the 16 with skin-limited LCH went on to multisystem involvement; the other 15 experienced complete resolution of their skin disease by age 7 months (J Pediatr Hematol Oncol. 2014 Nov;36(8):613-6). The other study included 71 patients with skin-involved LCH; none of the 21 patients with the skin-limited variety progressed to multisystem LCH during 3 years of follow-up (J Pediatr. 2014 Nov;165[5]:990-6).

“It’s very rare for patients who present with skin-limited LCH alone to develop multisystem disease and to require chemotherapy or other more aggressive treatment,” Dr. Huang said. “I think that skin-limited LCH is probably a separate entity with its own natural history distinct from multisystem disease. We can see that with current genomic testing: in multisystem LCH, BRAF mutations are identified in at least half of patients, but very few with skin-limited disease express those mutations.

“The clinical pearl here is if you have a patient with skin-limited LCH it very rarely progresses to multisystem involvement. It’s associated with a good prognosis. That doesn’t mean you shouldn’t monitor them, but I think it can be reassuring information for the family,” she said.